I switched from Monster Truck racing three years ago and started running 200mm. It is a lot of fun. I race in Cincinnati, Ohio at the TSRCAR club.
I do not know how much setup you use with 1/8 Buggy, but with On-Road racing, setup is very important and often very subtle changes can make a big difference.
The big setup adjustments are:
TIRE COMPOUNDS, SHOCKS, RIDE HEIGHT, DROOP
ROLL CENTERS, CAMBER, CASTER, TOE-IN
SWAY BARS, SHOCK OILS, SHOCK PISTONS, BODY DESIGN
A good setup systems is very important in my opintion:
HUDY MAKES A VERY GOOD ONE
TM MAGIC IS VERY GOOD AND MUCH CHEAPER
As far as expense...the largest expense beyond what you would normally spend in off road would be the Foam Tires. You will get about two maybe three runs out of a set for qualifing (depending on how ruff the surface) and you will most likely get one run out of a set for the Mains. At $12-$15 a pair, it adds up. Fuel would be the same, most of your tools would cary over as well as radio and electronic equipment. Most likley the starter box would work as well.
As far as tracks in your area, you are on Target...
Toledo has a fine facility.
Detroit may be on the way out.
Mentor, Ohio club is trying to keep something going.
Canada: Hamilton, Ontario has a very nice facility.
AND OF COURSE MY HOME TRACK IN Hamilton, Ohio www.TSRCAR.com
Hope this helps.